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High-Resolution Solar Radiation Datasets

Introduction

Solar radiation datasets with high spatial and temporal resolution have been developed. This data helps simulate solar photovoltaic system operation and study the short-term impact (< 5 minutes) of irradiance fluctuations on the energy production of a power plant or a neighbourhood of solar houses.

The measurement of solar radiation was performed at a high frequency (30-100 Hz or up to once every 10 milliseconds) to allow high ramp-rate events to be recorded. The datasets were retrieved from a network composed of 41 units that measure the solar irradiance, distributed among two systems at two Canadian sites. The first system is located in Varennes (Québec), and the second in Alderville (Ontario). The latter is co-located within a 1 MW sub-array of the 5 MW Alderville First Nations Solar Farm. These systems allow for the measurement of ground-level solar variability on a network of sensors distributed over a given surface.

Instrumentation and Sampling

The irradiance sensors are LI-COR LI-200S photodiode-type pyranometers installed on wirelessly communicating and autonomously powered remote units. Each unit has two irradiance sensors: the first for global horizontal irradiance, and the second for global tilted irradiance on an inclined plane. In Varennes, the inclined plane has a slope of 45° on the horizontal and faces south. In Alderville, the inclined plane has a slope of 30° on the horizontal (south-facing), which corresponds to the plane of irradiance for this array.

Each unit takes measurements every millisecond (1 ms), averages them over a period of 10 milliseconds, and saves the data when it changes by more than 5 W/m² since the last saved value. In addition, data is saved at 1-minute intervals. The units are synchronized using a GPS system to ensure that the unit-to-unit skew is less than 1 millisecond.

Data File Description

Data files are saved in CSV format (comma separated values) and correspond to each unit of the network. The system located in Varennes has 17 units, and 24 units are in Alderville.

Files are named by date and the identifier of the unit from which the data is collected. The location of each unit is saved in KML files, as described below. Data was taken on the date corresponding to the folder name containing the file (using the format yyyymmdd), from sunrise to sunset (civil twilight when the geometric centre of the sun is 6° below the horizon), for each unit of the corresponding site.

Table 1 shows the content of each column in the files.

Table 1 – Data files content and format
Column Content Format
1 Day yyyy-mm-dd
yyyy: year
mm: month of the year (1-12)
dd: day of the month (1-31)
2 Hour of the day, Eastern Standard Time (GMT-5:00) HH:mm:ss.nnn
HH: hours (0-23)
mm: minutes (0-59)
ss: seconds (0-59)
nnn: milliseconds (0-999)
3 Global horizontal irradiance, in W/m² Integer
4 Global tilted irradiance, in W/m² Integer

The available data corresponds to four categories of days observed in Varennes and Alderville. Table 2 categorizes the days based on cloud cover. Click on the date to download data files for the desired day type and location.

Table 2 – Available data categories
Cloud cover Varennes Alderville
Clear sky 2014-12-30 [ZIP 1.62 mb] 2015-03-24 [ZIP 10.9 mb]
Overcast 2014-10-21 [ZIP, 1.26 mb] 2015-02-08 [ZIP, 1.29 mb]
Variable 2015-02-26 [ZIP, 2.74 mb] 2015-10-08 [ZIP, 4.65 mb]
Very variable 2014-07-17 [ZIP, 10.5 mb] 2015-08-12 [ZIP, 15.5 mb]

KML Location File Description

Two KML files describe the location of each one of the 41 units in Varennes and Alderville. The file can be opened using Google Earth or the online tool Google Maps. The maps show the location of each unit on the two sites. Their coordinates are located at the bottom of this page.

Varennes Site

Because of the high sampling rate, the sensors are capable of measuring the effect of an obstruction passing over them, such as birds or insects. These events may cause a sudden drop in the measured irradiance on a unit. Some units are relatively close to obstructions (trees, power lines, etc.), which can also shade the sensors during certain times of the day and year. The identifier for the Varennes units begins with the letters VAR. The locations are shown in Figure 1.

Alderville Site

Similarly to Varennes, the sensors can be shaded, for instance, by birds or insects. However, the units are located in a more open area than in Varennes, and shading events caused by obstructions are less frequent. The identifier for the Alderville units begins with the letters AFN. The locations are shown in Figure 2 .

Map showing the unit locations in Varennes, QC

Figure 1 – Map showing the unit locations in Varennes

Map showing the unit locations in Alderville

Figure 2 – Map showing the unit locations in Alderville, ON

Unit Coordinates

Tables 3 and 4 list the coordinates (latitude and longitude) of each unit. Units VAR01 to VAR17 are located in Varennes, and units AFN01 to AFN24 are located in Alderville.

Table 3 – Coordinates of each unit located in Varennes
Unit identifier Latitude (°) Longitude (°)
VAR01 45.616084 -73.386362
VAR02 45.616760 -73.385428
VAR03 45.617659 -73.384157
VAR04 45.616777 -73.386646
VAR05 45.617206 -73.386011
VAR06 45.617509 -73.385312
VAR07 45.616783 -73.387937
VAR08 45.617202 -73.387311
VAR09 45.617689 -73.386657
VAR10 45.618096 -73.386048
VAR11 45.618569 -73.385269
VAR12 45.617297 -73.388603
VAR13 45.617682 -73.387882
VAR14 45.618080 -73.387298
VAR15 45.618513 -73.386500
VAR16 45.618561 -73.387829
VAR17 45.619610 -73.386530
Table 4 – Coordinates of each unit located in Alderville
Unit identifier Latitude (°) Longitude (°)
AFN01 44.190159 -78.096701
AFN02 44.190145 -78.096148
AFN03 44.190130 -78.095589
AFN04 44.190427 -78.096561
AFN05 44.190412 -78.096000
AFN06 44.190400 -78.095447
AFN07 44.190703 -78.096967
AFN08 44.190691 -78.096411
AFN09 44.190678 -78.095852
AFN10 44.190967 -78.096811
AFN11 44.190953 -78.096251
AFN12 44.190939 -78.095698
AFN13 44.191243 -78.097176
AFN14 44.191230 -78.096624
AFN15 44.191211 -78.095958
AFN16 44.191369 -78.096892
AFN17 44.191290 -78.096341
AFN18 44.191509 -78.097167
AFN19 44.191495 -78.096609
AFN20 44.191476 -78.095796
AFN21 44.191460 -78.095238
AFN22 44.191798 -78.097437
AFN23 44.191783 -78.096875
AFN24 44.191770 -78.096319

Acknowledgments

The data was collected by the CanmetENERGY laboratory in Varennes, as part of the High-Resolution Solar Radiation Time Series Generation (RENI-506) project. The location for system installation in Varennes was provided by the Hydro-Québec Research Institute (IREQ). The field in Alderville was provided by the Ojibway Alderville First Nation. Funding for this project was provided by the Government of Canada through the ecoENERGY Innovation Initiative (ecoEII).

 

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